Electromagnetic device having a movable element



July 17, 1962 A. R. DAv|s 3,045,152

ELECTROMAGNETIC DEVICE HAVING A MOVABLE ELEMENT Filed Feb. 6, 1959 2 Sheets-Sheet 1 i EN IN V EN TOR. 1442/64 Q DA ws July 17, 1962 A. R. DAVIS 3,045,152

ELECTROMAGNETIC DEVICE HAVING A MOVABLE ELEMENT Filed Feb. 6, 1959 2 Sheets-Sheet 2 IN V EN TOR.

I -LEV BY A/a ,e OAv/s United States Patent O 3,045,152 ELECTROMAGNETIC DEVICE HAVING A MOVABLE ELEMENT Ariel R. Davis, 3687 S. State St., Salt Lake City, Utah Filed Feb. 6, 1959, Ser. No. 791,696 7 Claims. (Cl. 317166) This invention relates to electromagnetic devices having a movable element responding to magnetic fields and is directed particularly to sensitive devices, such as meters, relays and solenoids.

In apparatus such as meters, relays, solenoid switches, and the like, having electromagnetic coils mounted between magnetic pole members, the variation in the current passing through the coil causes an actuation or change in the position of the coil. The coil movement may be utilized to measure current or to actuate contacts. Heretofore, in such devices the electromagnetic coil has been rotatably mounted on bearings or rotatably suspended by wires which `twist under the electromagnetic action. In order to secure the requisite sensitivity and durability, the structure of the mounting has been of necessity expensive. Further, the electromagnetic units are bulky and have an inappropriate shape for the close mounting of the indicating portion of the meter.

An object of this invention is to provide an electromagnetic device which is small in size, inexpensive, and v rugged in construction.

Another object of the invention. is to provide a rugged and inexpensive suspension of a moving electromagnetic coil in a magnetic field. f

Another object of the invention is to provide an electromagnetic device with a coil which moves linearly through the magnetic field.

Another object of the invention is to provide an isolated magnetic pole within the electromagnetic coil of an electromagnetic device.

Other objects of the invention will become apparent from the following description taken in connection with the drawings in which:

FIG. 1 is a side view of a linear embodiment of the invention;

FIGS. 2 and 3 illustrate the relationship between the magnetic flux and the electromagnetic coil;

FIG. 4 illustrates an exploded view of ameter or relay in accordance with the invention;

FIG. 5 illustrates a sectional view of the embodiment of FIG. 4 taken along lines 5--5 of FIG. 6;

FIG. 6 illustrates a sectional view taken along lines 6-6 of FIG. 5;

FIG. 7 illustrates a modication of the plates and magnetic members;

FIG. 8 illustrates a sectional view of a tubular form of the invention taken along lines 8 8 of FIG. 9; and

FIG. 9 is a sectional view of a tubular form taken along lines 9 9 of FIG. 8.

In the electromagnetic apparatus illustrated in the drawings the movable electromagnetic coil is mounted between outer ferromagnetic members and around an intermediate ferromagnetic member. The current passes around the coil so that it moves in opposite directions on opposite sides of the intermediate member. Magnetic flux extends between one outer member and the intermediate member and flux also extends between the other outer member and the intermediate member. The flux between one outer member and the intermediate member and the flux between the other outer member and the intermediate member extends in opposite directions, either from the outer members to the intermediate member or from the intermediate member to the outer members. In FIG. 2 the inner member is narrower than 3,645,152 Patented July 17, 1962 ICC the outer member and the tlux lines are indicated by dash lines. It will be noted from this illustration that the short magnetic flux lines extend straight across from the outer member to the inner member and an electric current cuts these flux lines passing through the coil. This creates a reaction torce pushing the coil normal to the paper in a vertical direction. The current in the portion of the winding underneath the intermediate member reacts with the ilux also to urge the coil in the same direction. The flux lines extending from the ends of the intermediate member are also substantially normal to the coil and the current passing through the coil correspondingly reacts with these ilux lines to urge the coil in the same direction. Thus, in allrelationships between the current in the coil and the magnetic ilux a force is developed actuating the coil in the same direction, thus imparting a linear movement to the coil along the intermediate member. All of the flux relative to the sector of location of the coil is coupled or intersected by the coil.

In FIG. l permanent magnets 1i), 11, 12 and 13 are interleaved between the outer members 14 and 15 and the intermediate member 16 to form spaces 17 and 18. The magnets have a short magnetic path within the magnet with the poles extending longitudinally to form a south pole on one magnet side and a north pole on the other side. The magnets are positioned so that the same pole is in contact with the intermediate member and the other pole is in contact Iwith the outer members. Thus, the lux from the north pole enters the intermediate member and then bridges across the spaces 17 and 18 to the outer members 14 and 15. Thus, the fluxes are extending outwardly from the intermediate member and in opposite directions. The electromagnetic coil 19 is wound to produce a current through the coil as described in connection with FIGS. 2 and 3. When a direct current is passed through the coil, the coil is moved either in one direction or the other depending upon the direction of the current through the coil. As previously described, the reaction forces of the coil are all in the same direction and thus impart to the electromagnetic coil a linear movement parallel to the intermediate member. The coil may be mounted on the end of a pivotally supported needle and as the coil is actuated, the needle is moved about the point of suspension to indicate variations in current.

In FIG. 4 an exploded view of another embodiment of the inventionis illustrated. In this embodiment the coil is mounted on a non-magnetic flat, spring strip 34. A base 25 is provided and upper and lower ferromagnetic plates 26 and 27 are mounted thereon. Between the ferromagnetic plates an intermediate ferromagnetic plate 28 is positioned and spaced from the upper and lower plates by the permanent magnets 29, 30, 311 and 32. The magnets are related to the plates in the same manner as in the previous embodiment. The permanent magnets are preferably of the ceramic-type and may have a tapered shape to providetapered spaces between the upper and lower plates and the intermediate plate for receiving the movement of the electromagnetic coil. The upper and lower plates 26 and 27 preferably have a rectangular shape and the intermediate plate 28 has large notches formed therein so that the intermediate plate has a small area for receiving the flux from the outer plates. The intermediate plate is thus shaped to provide an isolated pole with a uniform concentrated flux. The electromagnetic coil 33 is mounted on a thin, ilat strip 3-4 having an opening to tit the coil and strip around the inter-mediate plate. The

strip is made of a spring material, such as bronze. The

he end of the strip, respectively, to firmly hold the strip to have a planar movement. The projection may be increased in thickness or made into a solid end attached to the base to reduce the resiliency and stiffen the pivotal action. The strip may be provided with an extension in the opposite end of the mounting or at any other suitable point to indicate the position of the coil or utilize the motion for any useful purpose. r[he resiliency of t.e mounting returns the unit to a neutral position.

The electromagnetic coil 33 may be several coils. These coils may be connected in series to form a single electromagnetic means or may be connected to form a differential meter or relay.

The plate 23 is preferably formed to have a reduced area between the upper and lower plates 2d and 27. In this embodiment the intermediate plate is provided with notches 3S and 39 to form the reduced portion dit of the intermediate plate. As previously described in the description of FIGS. 2 and 3, the lines of force between the upper and lower plates 2e and 27 and the reduced portion L?? of the intermediate plate are as illustrated. Thus, all the actuating forces acting on the coils and strips are in the same direction so that a planar or linear motion is imparted to the movable member formed by the coils and strip. The ux extends from the opposite sides of the intermediate plate 4t? to the upper and lower plates. These flux `lines are substantially straight. At the edges 41 and f1.2 of the area 4t) the flux lines extend in a curved manner and also extend from the edges il and d2 as shown in FIGS. 2 and 3. These curved end uxes are also cut by the current in a transverse manner to produce an actuating force in the same `direction as that produced by the portions of the coil between the portion dit and the upper and lower plates. The flux extending from the reduced portion iii and encompassed by the coils 33 forms an isolated magnetic pole and is cut by movement of the coils.

Forms of pivotally mounting the strip 34 other than by the two projections 35 and 36 may be used. The strip may be solid or thickened to control the restoring torque.

At the other end of the unit an extension 43 of the base may be provided with a scale 44 to measure the movement of the pointer 45 extending from the end of the strip 34. The structures of the coils and the linx-carrying members produce a linear proportional movement of the pointer 45. Further, due to the rugged and simple mounting of the strip on the base 25', a rugged, yet sensitive, meter may be produced. Further, the laminated structure of the pole pieces Zt, 36, 3l and 32 permits the design of a thin, tlat meter. This permits a plurality of meters to be stacked horizontally or vertically in close relation, thereby providing a large number of meters within a short distance and which are close together for purposes of viewing. For movement of the pointer i5 in a vertical plane a counterforce or weight is provided to balance the coil.

The unit may also be readily adapted as a sensitive polarized relay by providing contacts Lid and 47. The strip 34 may be used to carry the current for transference to the contacts 46 and 47. This current does not affect the movement since the current passes on both sides of the intermediate plate in the same direction and any forces created by this current cancel one another.

The base 2S and extension 43 are preferably made of a non-magnetic, non-conductive material and the plates 26, 27 and 2S have ferromagnetic properties. The magnets 29, 3i?, 31 and 32 are preferably of the permanent ceramic type. However, electromagnetic coils may be substituted for the permanent magnets to produce the flux. As illustrated, the plates 26, 2,7 and 23 are flat. However, it may be preferable to have recesses as shown in FiG. 7 to shorten the magnetic path between the upper and lower plates and the intermediate plate and extend the edges of the magnet beyond the edges of the plates to lengthen the exterior linx path.

ln FIGS. 8 and 9 the adaptation of the invention to a solenoid construction is shown in which the outer cylindrical member 50 provides or receives iiuX to or from the inner cylindrical member Sl. Electromagnetic coils and are provided to create the flux in the cylindrical members 50, 51 and the flat disc end members 56, 57. On opposite ends of the member 51 the flux is extending in opposite directions. In the space 52 between the outer tubular member 50l and the inner member 51 a circularshaped electromagnetic coil S3 may be provided. The wire is wound in the coi 53 to produce a current traveling in the same direction around the center member 51. Thus, over each sector the current is cutting the flux in the same manner to produce actuating forces on all parts of the coil in the same direction and thus impart a linear motion to the coil. The center member 51 is thus er1- compassed by the electromagnetic coil 53 and forms an isolated pole. The coil 53 may be mounted on a nonmagnetic bearing to move parallel to the members 50 and 5l. Thus, a sensitive, yet rugged mounting of the coil is accomplished, since the electromagnetic coil has a linear movement.

It is thus seen from the foregoing embodiments that an electromagnetic unit having a linear movement to the moving element is provided. This linear movement permits an inexpensive mounting of the moving element by means of various mountings pivotally swinging the element without the use of bearings. Further, the linear movement permits a more versatile shaping of the unit for adaptation to various physical requirements when mounting the unit so that the unit has small dimensions when necessary. In addition to the parallel motion of the moving element, a better utilization of the magnetic flux is achieved in that an isolated pole member is formed and all flux `lines encompassed by the element are utilized to provide an actuating force.

Various adaptations and designs may be made from the invention as set forth in the foregoing description without departing from the scope of the invention as defined in the appended claims.

I claim:

l. An electromagnetic device comprising outer ferromagnetic plates and an intermediate ferromagnetic plate positioned between said outer plates and spaced therefrom to form spaces on each side of said intermediate plate, flux-producing means positioned between said plates forming said intermediate plate solely of one polarity and `said outer plates solely of the opposite polarity for creating flux passing through said spaces between said outer members and said intermediate member with the ux in one space extending in the opposite direction to the flux in the other space to form an isolated magnetic pole, electromagnetic means for passing an electric current positioned between said intermediate plate and said outer plates in the spaces for-med thereby to intersect all the lines of flux between said plates at the sector of location of the electromagnetic means and on passing electric current creating ux to relatively move said plates and said electromagntic means in response to the electric current passing through said electromagnetic means.

2. An electromagnetic -device as set forth in claim l wherein said intermediate plate has a reduced flux area less than the area of said outer ferromagnetic plates to produce a concentrated isolated magnetic pole encompassed by said electromagnetic means.

3. An electromagnetic device as set forth in claim 2 wherein said flux-producing means has a tapered shape extending vlongitudinally to said intermediate plate and said electromagnetic means is pivotally mounted at one end to move between said flux-producing means.

4. An electromagnetic device comprising a non-magnetic base portion, first and second outer ferromagnetic plates mounted on said base portion and an intermediate ferromagnetic plate positioned between said outer plates, said intermediate plate having notches at opposite ends to form a reduced area, concentrated flux-producing means positioned between said first outer plate and said second outer plate, an electromagnetic coil wound around said reduced area and movable in relation thereto producing currents moving in opposite directions on opposite sides of said reduced portion, said flux-producing means producing a flux extending in opposite directions between said intermediate plate and said outer plates to produce a linear force on said coil on passage of current therethrough.

5. An electromagnetic device as set forth in claim 4 wherein a resilient mounting means is provided attached to said base and pivotally supporting said coil to return said coil to neutral position.

6. An electromagnetic ydevice as set forth in claim 5 wherein said resilient member comprises a metal strip having an opening therethrough to position the strip on opposite sides of said intermediate plate for passing current in the same direction without iniiuencing the strip.

7. An electromagnetic device comprising an outer tubular ferromagnetic member forming one pole and an inner cylindrically-shaped ferromagnetic -member forming an annular space with sai-d outer member, said inner member forming the other pole, ferromagnetic means producing a ux having a substantially uniform density between said inner and outer members, an electromagnetic coil wound to produce a current circulating around said inner member and having means for supporting said coil in said space so that said coil moves axially in linear increments on passage of current therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 1,063,950 Berdon June 1G, 1913 2,556,816 Lukacs June 12, 1951 2,833,968 Karlson May 6, 1958 2,869,049 Dietz et al Jan. 13, 1959 

